The upstream fix is now queued: commit d58384c22739, "PCI: Fix BAR resize for devices on a root bus", in Bjorn Helgaas's PCI tree (git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git, branch pci/for-linus), committed 2026-09-18 for the current 7.3 cycle. Reviewed-by: Ilpo Järvinen, Cc: stable. Patch thread: https://patch.msgid.link/[email protected]
Request: please cherry-pick this into both affected Ubuntu 7.0 kernels: the resolute 7.0 kernel and linux-hwe-7.0 in noble, which is installed by default from the 24.04.5 point release, so this reaches a default install and not just opt-in HWE users. Upstream stable will only carry the fix to 7.2.y (6.19.y, 7.0.y and 7.1.y are EOL), so it will not arrive via a 7.0.y stable update. Impact: when a device sits directly on a PCI root bus (bus->self == NULL, e.g. the SolidRun HoneyComb LX2K, where the AMD dGPU has no root port), pci_resize_resource() releases the device's BARs and returns success without reassigning them. amdgpu then fails init (gmc_v8_0 sw_init failed -19). Regression introduced upstream by 337b1b566db0 (v6.19). Fix: with no upstream bridge, call pci_bus_assign_resources() on the root bus to place the released BARs. It also fixes an unbalanced pci_bus_sem up_read() on that path. Testing: applied to the resolute 7.0.0-31.31 source (hunk offsets only), built with pdebuild and booted on the affected hardware. amdgpu initializes with the full 4096M BAR with the amdgpu.rebar=0 workaround removed. I also exercised the resize path directly via the resource0_resize sysfs attribute, shrinking to 256M and growing back to 4G, with a clean release/assign each way. Regression potential: confined to pci_do_resource_release_and_resize(). The bridged path's logic is unchanged apart from taking pci_bus_sem before the BAR release loop. Workaround until then: amdgpu.rebar=0. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2159596 Title: amdgpu fails to come up due to BAR issue when at PCIe root To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2159596/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
